Canada completes second phase of IMSR design review

April 21, 2023, 7:00AMNuclear News
A rendition of Terrestrial Energy’s IMSR. (Image: NRC)

The Canadian Nuclear Safety Commission (CNSC) has completed phase two of its prelicensing vendor design review for Terrestrial Energy’s Integral Molten Salt Reactor (IMSR), the Ontario-based advanced nuclear technology firm announced Tuesday. Phase one of the VDR commenced in April 2016 and was completed in November of the following year.

The IMSR is molten salt–cooled and –fueled and can supply heat at 585°C via a tertiary molten salt loop for direct use in on-site electric power generation and energy-intensive processes, including desalination, hydrogen production, petrochemical refining, and clean synthetic transport fuels production. The reactor is designed to use standard-assay low-enriched uranium, avoiding the need for the high-assay form known as HALEU.

Review overview: According to Terrestrial, the VDR involved a comprehensive examination of the IMSR design covering 19 “focus areas” defined by the CNSC and required preparation of hundreds of technical submissions. Its scope included a systematic review of Terrestrial’s engineering management processes; confirmatory testing program for IMSR components and systems; reactor controls and safety systems; defense-in-depth strategy; safety analysis; and the requirements for safeguards, security, fire protection, and radiation protection.

Following an extensive multiyear review, CNSC staff concluded that there are no fundamental barriers to licensing the IMSR plant, the company said.

Confident Canadians: “The VDR is a comprehensive prelicensing regulatory review, and its completion is a breakthrough for Terrestrial Energy,” said Simon Irish, the company’s chief executive officer. “Its scope and conclusion provide commercial confidence to proceed to licensing and construction of IMSR plants. It is the first technology review completed by a major regulator of a nuclear plant design that uses a Generation IV reactor technology to supply heat at high temperature, and the first time for molten salt reactor technology. This review is a major step to bring molten salt technology to commercial markets and IMSR plants to large industrial companies seeking practicable high-impact solutions to decarbonize industrial production.”

Stephen Harper, a Terrestrial advisory board member (and Canada’s 22nd prime minister, 2006–2015), termed the review’s completion “a proud moment for Canada,” adding, “It points to a different direction of travel for nuclear energy, away from the traditional modes of development and use. The nuclear age will be renewed with high-temperature reactor technologies designed and developed by innovative private companies to achieve competitive commercial performance in civilian markets. This landmark brings that one step closer.”

In case you missed it: In November 2022, Terrestrial announced the signing of a letter of intent with TerraPraxis, a U.K.-based nonprofit devoted to climate solutions, to cooperate on the latter’s Repowering Coal initiative—a program aimed at integrating clean heat sources with existing infrastructure at coal-fired power plants in North America and elsewhere. The initiative was developed with partners Bryden Wood, the Massachusetts Institute of Technology, Microsoft, Schneider Electric, University at Buffalo, and others.

And in June 2022, Terrestrial announced that the Nuclear Regulatory Commission and the CNSC had completed a first joint technical review of the IMSR.

The IMSR was selected in December 2019 to be the first advanced non–light water nuclear reactor technology to be studied under an August 2019 NRC/CNSC memorandum of cooperation aimed at enhancing regulatory effectiveness through collaborative work on technical reviews of advanced reactor and small modular reactor technologies.


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